1. Field of the Invention
The present invention relates to a method for predicting the immune response in a mammal to neoplastic disease based on the expression profile of tumor necrosis factor receptor (TNF-R) superfamily mRNA in neoplastic tissue, and of tumor necrosis factor (TNF) superfamily mRNA in circulating leukocytes. In the method, samples of neoplastic tissue are obtained and the TNF-R superfamily subtype mRNAs expressed in those tissues are assessed. Furthermore, whole blood of the mammal is subjected to a stimulus that activates T-cells in the blood and the TNF superfamily subtype mRNAs that exhibit a significant change in expression level in response to the stimulus are identified. Individuals that exhibit a change in expression level in TNF superfamily subtypes that correlate with the TNF-R superfamily subtypes expressed in their tumor tissue are determined to have a likely lesser severity of prognosis for their disease.
2. Description of the Related Art
Different modalities of cancer therapies may be compared to varying types of uses of force in society. Chemotherapy is like the widespread use of military force in a city; the overwhelming power of the weapons involved may cause collateral damage to civilians. In contrast, leukocytes in circulating peripheral blood, which are the primary killers of cancer cells in the human body, are like police officers patrolling city streets who deal with street crime. Likewise, when leukocytes encounter cancer cells in the body, these cells are the initial responders to the cancer targets. Leukocytes are classified into many classes and subclasses based on morphological analysis and characterization of cell surface markers using flow cytometry or immunohistochemical staining techniques. These classes and subclasses are like identifying police officers by their uniforms and identification budges. The number of leukocytes per mm3 of peripheral blood corresponds to the number of officers in the city.
When a police officer encounters street criminals, he must deal with them with the weapons he has at hand. But police officers are not always carrying appropriate weaponry. Similarly, cytotoxic T-cells are not always provided with the proper anti-tumor factors to combat specific cancer cells. Cytotoxic T-cells recognize cancer cells via IgG Fc receptors (FcγR), when the cancer cells are coated with IgG. This process is termed antibody-dependent cell-medicated cytotoxicity (ADCC). In fact, IgG is frequently recognized around cancer margins by staining with anti-human IgG (see, for example, Richman A V, Immunofluorescence studies of benign and malignant human mammary tissue, J. Natl. Cancer Inst. 1976; 57:263-7, and Koneval T, et al., Demonstration of immunoglobulin in tumor and marginal tissues of squamous cell carcinomas of the head and neck, J. Natl. Cancer Inst. 1977; 59:1089-97). Infiltration of mononuclear leukocytes into cancer lesions is also found in many cases. The FcγR on the surface of cytotoxic T-cells are like a bag containing an assortment of weapons that a police officer carries. Different types of FcγR, such as CD16, CD32, and CD64 correspond to different types of bags. Cudgels are an initial weapon, and are held ready to attack at any time. In cytotoxic T-cells, the cudgel corresponds to perforin (see Nakanishi et al., Perforin expression in lymphocytes infiltrated to human colorectal cancer, Br. J. Cancer 1991; 64:239-42), which is pre-synthesized and stored in the cytosol of cytotoxic T-cells, and immediately released upon FcγR activation. Other presynthesized “cudgels” ready for use include granzymes, proteases related to the digestive enzymes trypsin and chymotrypsin, which may act to trigger apoptosis in the target cell.
Officers also carry more powerful guns, which may correspond to tumor necrosis factors (TNF) in cytotoxic T-cells. Usually, the “bullets” in the cellular context (TNF subtypes) are not loaded in the gun, and are synthesized and released from cytotoxic T-cells only upon Fc receptor activation. TNF is capable of inducing apoptosis by interacting with specific TNF receptors present on the surface of target cells. In order to maintain killing activities against a broad spectrum of target cells, different types of TNF ligands exist (as part of a TNF superfamily, abbreviated to TNFSF). According to GenBank and UniGene information (http://www.ncbi.nlm.nih.gov), the human TNF superfamily encompasses up to TNF superfamily 18, with some missing numbers (16 and 17) and multiple sequences within the same number (13A and 13B), for a total of 17 human members. For the corresponding TNF receptors (the TNF-R superfamily: abbreviated to TNFRSF), the human TNF-R superfamily encompasses up to TNF-R superfamily subtype 21. Although TNF/TNF-R superfamily subtype interactions are not strictly specific, each ligand generally reacts with a specific receptor, as shown in Table 1, and over 300 different TNF superfamily subtype TNF-R superfamily combinations exist.
TABLE IList of GenBank UniGene entry of TNFRSF and TNFSF mRNA.TNFRSF (UniGene #)Corresponding TNFSF (UniGene #)1A(Hs.279594)2(Hs.241570)1B(Hs.256278)2(Hs.241570)3(Hs.1116)1(Hs.36)3(Hs.376208)4(Hs.129780)4(Hs.181097)5(Hs.472860)5(Hs.652)6(Hs.244139)6(Hs.2007)7(Hs.355307)7(Hs.501497)8(Hs.1314)8(Hs.494901)9(Hs.193418)9(Hs.1524)10A(Hs.401745)10(Hs.478275)10B(Hs.521456)10(Hs.478275)10C(Hs.119684)10(Hs.478275)10C(Hs.119684)10(Hs.478275)10D(Hs.213467)10(Hs.478275)11A(Hs.204044)11(Hs.333791)11B(Hs.81791)11(Hs.333791)12A(Hs.355899)12(NM003809)*14(Hs.512898)14(Hs.129708)17(Hs.2556)13(Hs.54673)13B(Hs.525157)18(Hs.212680)18(Hs.248197)25(Hs.462529)15(Hs.241382)*GeneBank accession number (no UniGene entry was found).
The complete eradication of cancers may happen when the appropriate TNF superfamily subtype is released from infiltrating cytotoxic T-cells. The rare cases of miracle survivors of cancers may be those in which the TNF superfamily subtype TNF-R superfamily subtype combination is perfect.
Antibody-dependent cell-mediated cytotoxicity (ADCC) is another mechanism involved in the cytolytic function of leukocytes in conjunction with antibodies (see Perussia et al., Assays for antibody-dependent cell-mediated cytotoxicity (ADCC) and reverse ADCC (redirected cytotoxicity) in human natural killer cells, Methods Mol. Biol. 2000; 121:179-92). Once the Fab portion of IgG binds to the target cells, the Fc portion of IgG activates Fc receptors on the leukocytes, followed by activation of these leukocytes to attack target cells. Although ADCC has been studied for many years, the conditions in in vitro experiments involving ADCC is dependent on the ratio between effector cytotoxic T-cells and target cells in a pure cell system suspended in an artificial solution. Moreover, because cytolysis was generally quantitated by the release of isotope (chromium-51) from the target cells, it was not known whether the observed cytolysis happens via perforin or TNF. It is also not known which TNF superfamily subtypes are involved in ADCC.
Finally, a further important mechanism by which leukocytes combat cancer is the release of chemokines to recruit more leukocytes to the disease site. Many such cytokines have been discovered. Although correlations have not been established between specific chemokines and specific populations of recruited leukocytes, the phenomenon of chemokine release and leukocyte recruitment is important in combating cancer. An analogy might be made here to policemen confronted with a gang of criminals, who radio back to headquarters for more reinforcements.
In sum, although complicated cellular mechanisms are required to educate appropriate subsets of leukocytes to be able to recognize specific cancer markers, and appropriate chemotactic factors should be released to attract these mature leukocytes to the lesion, actual cancer killing happens in two distinct ways. Immediate cancer killing takes place by the release of perforin from these leukocytes, followed by slow and sustained induction of apoptosis via the synthesis and release of TNF (see Vujanovic, Role of TNF family ligands in antitumor activity of natural killer cells, Int. Rev. Immunol. 2001 June; 20(3-4):415-37). TNF induces apoptosis via binding to the specific receptors on the target cell surface. This means that leukocytes must release specific TNF ligand(s) corresponding to the receptors present on the cancer cells. Although the usefulness of TNF/TNF receptor ratios as predictors of disease outcome has been considered (see McDermott, TNF and TNFR biology in health and disease, Cell. Mol. Biol. (Noisy-le-grand). 2001 June; 47(4):619-35), little is known about the profile of TNF receptors in cancer cells and induction of ligands in leukocytes, nor is it known how appropriate populations of leukocytes are recruited.